Flooding blamed on failure to upgrade sewers

John Emmerson, displaced by floods in Toll Bar, sleeps in an aid centre

By Richard Gray, Science Correspondent

12:01AM BST 08 Jul 2007

A failure to upgrade the country's crumbling drainage systems led to the widespread flooding that has devastated thousands of homes and left businesses near collapse, flood prevention experts say.

Years of underinvestment by the Government and local authorities in improving the creaking sewage systems beneath towns and cities left many areas unable to cope with heavy rainfall.

The problem has been exacerbated by poor flood risk forecasting, which currently focuses on rivers bursting their banks and not surface water accumulation which caused the recent floods in the north of England.

Flood risk experts claim last month's record rainfall uncovered major cracks in the Government's strategy for tackling flooding and should serve as a "wake-up call".

The Environment Agency (EA) is in charge nationally of flood prevention, building flood defences around major waterways and issuing warnings about rivers. Local authorities and water companies are responsible for maintaining drains and sewers.

Some sewers in urban areas are intended to cope with significant amounts of surface water, but on the whole sewers have been ignored as a flood risk. Little effort has been made to ensure surface water can run off safely without overwhelming them.

"These floods have revealed some considerable cracks between local authorities and the Environment Agency when it comes to dealing with surface water," said Professor Ian Cluckie, the chairman of the Government-funded Flood Risk Management Research Consortium and a hydrology researcher at Bristol -University.

"Drainage has become a bit of a botched job. There is no one who is responsible for forecasting drain blockage and rainfall flooding. Other countries such as China use central flood forecasting where all the agencies work together, but in the UK it has all been regionalised so it can be very patchy.

"The water companies and local authorities deal with the sewers while the Met Office and Environment Agency work together to predict flooding of rivers and build flood defences around them. It means that rain water drainage falls somewhere in between."

Flood prevention specialists and engineers believe that the EA's focus on building river flood defences has led to the maintenance of drainage systems being sidelined. It means that while rivers can now withstand considerable amounts of water, sewers flood easily with a relatively small increase in surface water.

The amount of money allocated to water companies to spend on the creaking sewage system has changed little over the past 10 years.

Nationally, Ofwat, the water regulator, allowed water companies to spend just £8.8 billion between 1999 and 2004 on sewage systems. Despite calls to increase the amount by more than £1 billion, they allocated the same sum for 2005 to 2010.

Flooding in Hull and Yorkshire, which has affected more than 28,000 homes and around 6,000 businesses and which is expected to leave a repair bill of £1.5 billion, has been largely caused by drainage problems as large amounts of rain water has gathered on the surface but had nowhere to go as drain grates and sewers have become blocked.

An unusually slow-moving area of low pressure has led to the unseasonably wet weather.

"The Government has concentrated on building river defences that can withstand floods of the severity that they only occur once in every 100 years," said Prof Cluckie.

"Drainage systems in some areas can only withstand floods that occur once a year or once every 10 years, so in comparison the level of protection is much lower.

This is because the drainage system was built primarily with water quality considerations in mind. Drains all have bars and grates over them and the sewers can block easily. This past couple of weeks should have been a wake-up call for the need to update the drainage systems."

Richard Thomas, director of flooding at engineering consultants Faber Maunsell, said: "When the losses caused by flooding are greater than the amount being spent to prevent flooding, it is clear that something needs to be done."

The EA insisted that tackling flooding due to surface water was the responsibility of local authorities. "These were exceptional floods, a one-in-150-year event," said a spokesman.

"Most of the flooding was due to surface water and 98 per cent of our defences worked incredibly well. The main problem was the drainage systems which is the responsibility of local authorities."